Electric motor driven tool for orthopedic impacting

ABSTRACT

An orthopedic impacting tool comprises a motor, an energy storage chamber, a striker, and an anvil. The motor stores energy in the energy storage chamber and then releases it, causing the striker to apply a controlled force on an adapter to create a precise impact for use in a surgical setting. The tool may further comprise a combination anvil and adapter. An energy adjustment control of the tool allows a surgeon to increase or decrease the impact energy. A light source and hand grips improve ease of operation of the tool.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of and claims priority under35 U.S.C. §120 on the U.S. patent application Ser. No. 14/099,447, filedDec. 6, 2013, the disclosure of which is incorporated by reference, nowabandoned which '447 application is a divisional application of U.S.patent application Ser. No. 13/790,870 (now U.S. Pat. No. 8,602,124),filed on Mar. 8, 2013, the disclosure of which is incorporated byreference, which '870 application was a continuation-in-part of andclaimed priority under 35 U.S.C. §120 on U.S. patent application Ser.No. 12/980,329 (now U.S. Pat. No. 8,695,726), filed on Dec. 29, 2010,and U.S. patent application Ser. No. 13/466,870 (now U.S. Pat. No.8,393,409), filed on May 8, 2012, the disclosures of which areincorporated by reference.

FIELD OF THE DISCLOSURE

The present disclosure relates to electric tools for impacting inorthopedic applications, and, more particularly, to an electric motordriven tool for orthopedic impacting that is capable of providingcontrolled impacts to a broach or other end effector.

BACKGROUND

In the field of orthopedics, prosthetic devices, such as artificialjoints, are often implanted or seated in a patient's body by seating theprosthetic device in a cavity of a bone of the patient. Typically, thecavity must be created before the prosthesis is seated or implanted, andtraditionally, a physician removes and or compacts bone to form thiscavity. A prosthesis usually includes a stem or other protrusion thatserves as the particular portion of the prosthesis that is inserted intothe cavity.

To create such a cavity, a physician may use a broach, which broachconforms to the shape of the stem of the prosthesis. Solutions known inthe art include providing a handle with the broach, which handle thephysician may grasp while hammering the broach into the implant area.Unfortunately, this approach is clumsy and unpredictable as beingsubject to the skill of the particular physician. This approach almostwill always inevitably result in inaccuracies in the location andconfiguration of the cavity. Additionally, the surgeon suffers fromfatigue in this approach due to the constant hammering. Finally, thisapproach carries with it the risk that the physician will damage bonestructure in unintended areas.

Another technique for creating the prosthetic cavity is to drive thebroach pneumatically, that is, by compressed air. This approach isdisadvantageous in that it prevents portability of an impacting tool,for instance, because of the presence of a tethering air line, air beingexhausted from a tool into the sterile operating field and fatigue ofthe physician operating the tool. Further, this approach, as exemplifiedin U.S. Pat. No. 5,057,112, does not allow for precise control of theimpact force or frequency and instead functions very much like ajackhammer when actuated. Again, this lack of any measure of precisecontrol makes accurate broaching of the cavity more difficult.

A third technique relies on computer-controlled robotic arms forcreating the cavity. While this approach overcomes the fatiguing andaccuracy issues, it suffers from having a very high capital cost andadditionally removes the tactile feedback that a surgeon can get from amanual approach.

A fourth technique relies on the author's own prior disclosures to use alinear compressor to compress air on a single stroke basis and then,after a sufficient pressure is created, to release the air through avalve and onto a striker. This then forces the striker to travel down aguide tube and impact an anvil, which holds the broach and or othersurgical tool. This invention works quite well, but, in the process oftesting it, does not allow for a simple method to reverse the broachshould it become stuck in the soft tissue. Further, the pressure of theair results in large forces in the gear train and linear motionconverter components, which large forces lead to premature wear oncomponents.

Consequently, there exists a need for an impacting tool that overcomesthe various disadvantages of the prior art.

SUMMARY OF THE INVENTION

In view of the foregoing disadvantages of the prior art, an electricmotor-driven orthopedic impacting tool configured to include all theadvantages of the prior art and to overcome the drawbacks inherenttherein is provided. The tool may be used by orthopedic surgeons fororthopedic impacting in hips, knees, shoulders and the like. The tool iscapable of holding a broach, chisel, or other end effector and gentlytapping the broach, chisel or other end effector into the cavity withcontrolled percussive impacts, resulting in a better fit for theprosthesis or the implant. Further, the control afforded by such anelectrically manipulated broach, chisel, or other end effector allowsadjustment of the impact settings according to a particular bone type orother profile of a patient. The tool additionally enables proper seatingor removal of the prosthesis or the implant into or out of an implantcavity and advantageously augments the existing surgeon's skill inguiding the instrument.

In an embodiment, an electric motor-driven orthopedic impacting toolcomprises a power source (such as a battery), a motor, a control means,a housing, a method for converting the rotary motion of the motor to alinear motion (hereafter referred to as a linear motion converter), atleast one reducing gear, a striker, a detent and an energy storagemeans, which energy storage means can include either compressed air or avacuum. The tool may further include an LED, a handle portion with atleast one hand grip for the comfortable gripping of the tool, an adapterconfigured to accept a surgical tool, and a battery. At least some ofthe various components are preferably contained within the housing. Thetool is capable of applying cyclic impact forces on a broach, chisel, orother end effector, or an implant and of finely tuning an impact forceto a plurality of levels.

In a further embodiment, the handle may be repositionable or foldableback to the tool to present an inline tool wherein the surgeon pushes orpulls on the tool co-linearly with the direction of the broach. This hasthe advantage of limiting the amount of torque the surgeon may put onthe tool while it is in operation. In a further refinement of the handgrip, there may be an additional hand grip for guiding the surgicalinstrument and providing increased stability during the impactingoperation.

In a further embodiment, the broach, chisel or other end effector can berotated to a number of positions while still maintaining axialalignment. This facilitates the use of the broach for various anatomicalpresentations during surgery.

In a further embodiment, the energy storage means comprises a chamber,which is under at least a partial vacuum during a portion of an impactcycle.

In a further embodiment the linear motion converter uses one of a slidercrank, linkage mechanism, cam, screw, rack and pinion, friction drive orbelt and pulley.

In an embodiment, the linear motion converter and rotary motor may bereplaced by a linear motor, solenoid or voice coil motor.

In an embodiment, the tool further comprises a control means, whichcontrol means includes an energy adjustment element, and which energyadjustment element may control the impact force of the tool and reduceor avoid damage caused by uncontrolled impacts. The energy may beregulated electronically or mechanically. Furthermore, the energyadjustment element may be analog or have fixed settings. This controlmeans allows for the precise control of the broach machining operation.

In an embodiment the anvil and the adapter comprise a single element, orone may be integral to the other.

In an embodiment the tool may have a lighting element to illuminate awork area and accurately position the broach, chisel, or other endeffector on a desired location on the prosthesis or the implant.

In an embodiment the tool may also include a feedback system that warnsthe user when a bending or off-line orientation beyond a certainmagnitude is detected at a broach, chisel, or other end effector orimplant interface.

In an embodiment the tool may also include a detent that retains thestriker and which may be activated by a mechanical or electrical meanssuch that the energy per impact from the tool to the surgical endeffector is increased. In an embodiment, the characteristics of thisdetent are such that within 30% of striker movement, the retention forceexerted by the detent on the striker is reduced by 50%.

These together with other aspects of the present disclosure, along withthe various features of novelty that characterize the presentdisclosure, are pointed out with particularity in the claims annexedhereto and form a part of the present disclosure. For a betterunderstanding of the present disclosure, its operating advantages, andthe specific objects attained by its uses, reference should be made tothe accompanying drawings and detailed description in which there areillustrated and described exemplary embodiments of the presentdisclosure.

DESCRIPTION OF THE DRAWINGS

The advantages and features of the present invention will become betterunderstood with reference to the following detailed description andclaims taken in conjunction with the accompanying drawings, wherein likeelements are identified with like symbols, and in which:

FIG. 1 shows a perspective view of an orthopedic impacting tool inaccordance with an exemplary embodiment of the present disclosure inwhich a motor, linear motion converter, and vacuum as energy storagemeans are used;

FIG. 2 shows an exemplary position of the piston wherein the vacuum hasbeen created in accordance with an exemplary embodiment of the presentdisclosure;

FIG. 3 shows the striker being released and the striker moving towardsimpacting the anvil in accordance with an exemplary embodiment of thepresent disclosure;

FIG. 4 shows the vacuum piston moving back towards a first position andresetting the striker in accordance with an exemplary embodiment of thepresent disclosure;

FIG. 5 shows an orthopedic impacting tool in accordance with anexemplary embodiment of the present disclosure in which a compressionchamber is used to create an impacting force;

FIG. 6 shows an orthopedic impacting tool in accordance with anexemplary embodiment of the present disclosure in which a valve is usedto adjust the energy of the impact of the striker; and

FIG. 7 shows a comparison of the force vs. time curve between a sharpimpact and a modified impact using a compliance mechanism in accordancewith an exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

The best mode for carrying out the present disclosure is presented interms of its preferred embodiments, herein depicted in the accompanyingfigures. The preferred embodiments described herein detail forillustrative purposes are subject to many variations. It is understoodthat various omissions and substitutions of equivalents are contemplatedas circumstances may suggest or render expedient, but are intended tocover the application or implementation without departing from thespirit or scope of the present disclosure.

The terms “a” and “an” herein do not denote a limitation of quantity,but rather denote the presence of at least one of the referenced items.

The present disclosure provides an electric motor-driven orthopedicimpacting tool. The tool includes the capability to perform single andmultiple impacts as well as impacting of variable and varyingdirections, forces and frequencies. In an embodiment the impact force isadjustable. In another embodiment a detent may be provided, which detentfacilitates the generation of a higher energy impact. In yet anotherembodiment the impact is transferred to a broach, chisel, or other endeffector connected to the tool.

The tool may further include a housing. The housing may securely coverand hold at least one component of the tool. In an embodiment, thehousing contains a motor, at least one reducing gear, a linear motionconverter, a gas chamber, a striker, a force adjuster, a control means,and an anvil.

The tool further may include a handle portion with at least one handgrip for comfortable and secure holding of the tool while in use, and anadapter and a battery. The tool may further comprise a lighting elementsuch as an LED to provide light in the work area in which a surgeonemploys the tool. The anvil may be coupled to a broach, chisel or otherend effector through the use of an adapter, which adapter may have aquick connect mechanism to facilitate rapid change of differentbroaching sizes. The anvil may further include a locking rotationalfeature to allow the broach to be presented to and configured atdifferent anatomical configurations without changing the orientation ofthe tool in the surgeon's hands.

Referring now to FIGS. 1 through 4, in an embodiment, the linear motionconverter 12 comprises a slider crank mechanism, which slider crank isoperatively coupled to the motor 8 and reducing gears 7. The toolfurther comprises a vacuum chamber 23 that accepts a piston 24 which maybe actuated by the linear motion converter 12. It will be apparent thatthe piston 24 may be actuated in more than one direction. The vacuum iscreated in the vacuum chamber 23 by the movement of piston 24 away fromstriker 25. The vacuum created in the vacuum chamber 23 is defined as apressure of less than 9 psia for at least a portion of the operationalcycle.

In an embodiment, the motor 8 of the tool causes the linear motionconverter 12 to move, which pulls a vacuum on the face of the striker 25and creates at least a partial vacuum in the vacuum chamber 23, as isshown in FIG. 2. The piston 24 continues to move increasing the size ofthe vacuum chamber 23 until it hits a forward portion of the striker 25(i.e., a portion of the strike that is proximate to the end effector orpatient), which dislodges the striker 25 from its detent 10 and allowsit to rapidly accelerate towards the end of the tool that is proximateto the end effector or patient. In an embodiment, the detent may bemechanical, electrical, or a combination thereof, with the preferreddetent shown in the figures as a magnet. A characteristic of the detent10 is that once the detent 10 is released or overcome, the retentionforce of the detent 10 on the striker 25 reduces by at least 50% withinthe first 30% movement of the striker 25. The impact of the striker 25on the anvil 14 communicates a force to the adapter 1 and the broach,chisel or other orthopedic instrument.

In an embodiment, the direction of the force on the anvil is controlledby the user's (such as a surgeon) force on the tool and a stroke limiter13. It has been determined that prior art tools may occasionally getstuck in a cavity and the impact of the striker in the aforementionedparagraph may be insufficient to dislodge the tool. This embodiment hasthe unexpected benefit of easily dislodging tools and instruments thathave become stuck in a surgical cavity, while retaining all the benefitsof the existing tool in terms of precision-controlled impacting. A user,such as a surgeon, may hold the tool by the hand grip 29 or grips andutilize the light emitted by an attached light source 30, such as anLED, to illuminate a work area of the tool. In an embodiment, the lightsource and/or other components of the tool may be powered by a powersource, such as a battery 31.

In a further embodiment, an electromagnet may be incorporated as thedetent 10 and released at an appropriate point in the operation cycle toallow the striker 25 to impact the anvil 14. Once the striker 25 hasbeen released from the detent 10, the air pressure on the rearward sideof the striker 25, propels it forward to impact the anvil 14 or otherstrike surface. The resultant force may be communicated through an endof the anvil 14 that is proximate to the anvil strike surface 16 and,optionally, through the adapter 1 to which a broach, chisel, or otherend effector for seating or removing an implant or prosthesis may beattached.

The striker guide 11 may also have striker guide vent holes 20, whichallow the air in front of the striker 25 to escape, thus increasing theimpact force of the striker 25 on the anvil 14. The striker guide ventholes 20 may vent within the cavity of the tool body, thus creating aself-contained air cycle preventing air from escaping from the tool andallowing for better sealing of the tool. The position and the size ofthe striker guide vent holes 20 can also be used to regulate the impactforce. Further, it was unexpectedly found that adding the striker guidevent holes 20 increases the impact force of the striker 25 on the anvil14.

In an embodiment, as the piston 24 continues through its stroke it movestowards the rear direction, which movement brings it in contact with arear face of striker 25 and moves it towards the rear of the tool. Thisallows the detent 10 to lock or retain the striker 25 in position forthe next impact. Upon the piston 24 completing its rearward stroke, themotor 8 will preferably stop such that the piston 24 rests at or nearbottom dead center of the vacuum chamber 23. The vacuum chamber 23preferably has a relief or check valve 9 or other small opening, which,in an embodiment, is part of the piston 24. The valve 9 may also belocated at other points in the vacuum chamber 23 and allows for any airwhich may have accumulated in the vacuum chamber 23 to be purged out ofthe vacuum chamber 23 during each cycle. In a further embodiment thisvalve effect could be accomplished with a cup seal instead of an o-ringseal. This ensures that approximately atmospheric pressure is present inthe vacuum chamber 23 at a starting point in the operational cycle, thusensuring that each impact utilizes the same amount of energy, as isimportant in orthopedic impacting for at least the reason that itassures of a substantially consistent force and impact rate inmulti-impact situations.

In a further embodiment, the motor 8 of the tool causes the linearmotion converter 12 to move the piston 24 until the piston 24 moves asufficient distance such that the forward portion of the piston impactsa portion of the striker 25 and overcomes the detent 10 that retains thestriker 25 in the rear position. Once the striker 25 has been releasedfrom the detent 10, the vacuum in the vacuum chamber 23 exerts a forceon the striker 25, which accelerates the striker 25, causing the striker25 to slide axially down a cavity internal to the tool housing andstrike the anvil strike surface 16. FIG. 3 shows the striker 25imparting a force on the anvil strike surface 16, which causes a forwardmovement of the anvil 14 and/or tool holder. A resultant force may becommunicated through an end of the anvil 14 that is proximate to theanvil strike surface 16 and, optionally, through the adapter 1 to whicha broach, chisel, or other end effector for seating or removing animplant or prosthesis may be attached.

In another embodiment, the impact force may be generated using acompressed air chamber 5 in conjunction with a piston 6 and striker 4,as shown in FIGS. 5 and 6. In this embodiment, the motor 8 of the toolcauses the linear motion converter 12 to move the piston 6 untilsufficient pressure is built within the compressed air chamber 5 that isdisposed between the distal end of the piston 6 and the proximate end ofthe striker 4 to overcome a detent 10 that otherwise retains the striker4 in a rearward position and or the inertia and frictional force thatholds the striker 4 in that rearward position. Once this sufficientpressure is reached, the pressure accelerates the striker 4, whichstriker 4 slides axially down a cavity and strikes the anvil 14. Theresultant force is communicated through the end of the anvil 14 that isproximate to the anvil strike surface 16 and, optionally, through theadapter 1 to which a broach, chisel, or other device for seating orremoving an implant or prosthesis may be attached.

As the piston 6 continues through its stroke, it moves towards the reardirection, pulling a slight vacuum in compressed air chamber 5. Thisvacuum may be communicated to the back side of the striker 4, creating areturning force on the striker 4, which returning force causes thestriker 4 to move in a rear direction, i.e., a direction away from thepoint of impact of the striker 4 on the anvil strike surface 16. In theevent that an adapter 1 is attached to the anvil 14, a force may becommunicated through the adapter 1 to which the broach, chisel, or otherend effector for seating or removing an implant or prosthesis isattached.

The tool may further facilitate controlled continuous impacting, whichimpacting is dependent on a position of a start switch (which startswitch may be operatively coupled to the power source or motor, forexample). For such continuous impacting, after the start switch isactivated, and depending on the position of the start switch, the toolmay go through complete cycles at a rate proportional to the position ofthe start switch, for example. Thus, with either single impact orcontinuous impacting operational modes, the creation or shaping of thesurgical area is easily controlled by the surgeon.

The tool is further capable of tuning the amount of impact energy percycle by way of, for example, an energy control element 18. Bycontrolling the impact energy the tool can avoid damage caused byuncontrolled impacts or impacts of excessive energy. For example, asurgeon may reduce the impact setting in the case of an elderly patentwith osteoporosis, or may increase the impact setting for more resilientor intact athletic bone structures.

In an embodiment, the energy control element 18 preferably comprises aselectable release setting on the detent 10 that holds the striker 4 or25. It will be apparent that the striker 4 or 25 will impact the anvil14 with greater energy in the case where the pressure needed to dislodgethe striker 4 or 25 from the detent 10 is increased. In anotherembodiment, the detent 10 may comprise an electrically controlledelement. The electrically controlled element can be released atdifferent points in the cycle, thus limiting the size of the vacuumchamber 23, which is acting on the striker 4 or 25. In an embodiment,the electrically controlled element is an electromagnet.

In another embodiment, the vacuum chamber 23 or compressed air chamber 5may include an energy control element 18, which takes the form of anadjustable leak, such as an adjustable valve. The leakage reduces theamount of energy accelerating the striker 4 or 25, thus reducing theimpact energy on the anvil 14. In the case of the adjustable leak,adjusting the leak to maximum may give the lowest impact energy from thestriker 4 or 25, and adjusting to shut the leak off (zero leak) may givethe highest impact energy from the striker 4 or 25.

The tool may further comprise a compliance means inserted between thestriker 4 or 25 and the surgical end effector, which purpose is tospread the impact force out over a longer time period, thus achievingthe same total energy per impact, but at a reduced force. This can beseen clearly as a result of two load cell tests on the instrument asshown in FIG. 7. This type of compliance means can limit the peak forceduring impact to preclude such peaks from causing fractures in thepatient's bone. In a further embodiment, this compliance means may beadjustable and in a still further embodiment the compliance means may beinserted between striker 4 or 25 and the anvil 14 or surgical tool. Inthis manner and otherwise, the tool facilitates consistent axialbroaching and implant seating. Preferably, the compliance meansincreases the time of impact from the striker to at least 4 millisecondsand preferable 10 milliseconds. This contrasts to impacting in which avery high force is generated due to the comparatively high strengths ofthe striker 4 or 25 and the anvil 14 (both steel, for example).Preferably, the compliance means comprises a resilient material such asurethane, rubber or other elastic material that recovers well fromimpact and imparts minimal damping on the total energy.

In a further embodiment, the adapter 1 may comprise a linkagearrangement or other adjustment means such that the position of thebroach, chisel or other end effector can be modified without requiringthe surgeon to rotate the tool. In an embodiment, the adapter 1 mayreceive a broach for anterior or posterior joint replacement througheither an offset mechanism or by a rotational or pivotal couplingbetween the tool and the patient. The adapter 1 may thereby maintain thebroach or surgical end effector in an orientation that is parallel orco-linear to the body of the tool and the striker 25. The adapter 1 mayalso comprise clamps, a vice, or any other fastener that may securelyhold the broach, chisel, or other end effector during operation of thetool.

In use, a surgeon firmly holds the tool by the hand grip or grips andutilizes light emitted by the LED to illuminate a work area andaccurately position a broach, chisel or other end effector that has beenattached to the tool on a desired location on the prosthesis or implant.The reciprocating movement imparted by the tool upon the broach, chiselor other end effector allows for shaping a cavity and for seating orremoval of a prosthesis.

The tool disclosed herein provides various advantages over the priorart. It facilitates controlled impacting at a surgical site, whichminimizes unnecessary damage to a patient's body and which allowsprecise shaping of an implant or prosthesis seat. The tool also allowsthe surgeon to modulate the direction, force and frequency of impacts,which improves the surgeon's ability to manipulate the tool. The forceand compliance control adjustments of the impact settings allow asurgeon to set the force of impact according to a particular bone typeor other profile of a patient. The improved efficiency and reducedlinear motion converter loads allow use of smaller batteries and lowercost components. The tool thereby enables proper seating or removal ofthe prosthesis or implant into or out of an implant cavity.

The foregoing descriptions of specific embodiments of the presentdisclosure have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit thepresent disclosure to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. The exemplary embodiment was chosen and described in order tobest explain the principles of the present disclosure and its practicalapplication, to thereby enable others skilled in the art to best utilizethe disclosure and various embodiments with various modifications as aresuited to the particular use contemplated.

What is claimed is:
 1. An orthopedic impacting tool for striking anobject, the tool comprising: a motor; a linear motion converter; anenergy storage means, said energy storage means including a chamber,said chamber operating at less than 9 psia for at least a portion of acycle; a control means; an adapter, said adapter capable of holding abroach, chisel, reamer, or other surgical implement; and a striker,wherein said control means directs said motor to store an energy in saidenergy storage means and said energy storage means thereafter releasesthe energy onto said striker causing said striker to move from a firstposition to a second position such that said striker is capable ofimparting a force upon said adapter in at least one direction.
 2. Thetool as claimed in claim 1, wherein the tool further comprises a detent,said detent retaining said striker in said first position until saiddetent is released or overcome thus allowing said energy storage meansto release the energy onto said striker.
 3. The tool as claimed in claim2, wherein said detent comprises at least one of a magnet,electromagnet, solenoid, or mechanical interference.
 4. The tool asclaimed in claim 1, wherein said energy storage means further comprisesa valve.
 5. The tool as claimed in claim 1, wherein the tool furthercomprises an energy control element, said energy control element used toadjust the impact energy of said striker.
 6. The tool as claimed inclaim 1, wherein the tool further comprises a stroke limiter, saidstroke limiter limiting a stroke of said adapter to less than fiftypercent of a stroke of said striker.
 7. The tool as claimed in claim 1,wherein an axis of movement of said striker is parallel to an axis ofmovement of said adapter.
 8. An orthopedic impacting tool for strikingan object, the tool comprising: a linear motor; an energy storage means,said energy storage means including a chamber, said chamber operating atless than 9 psia for at least a portion of a cycle; a control means; asurgical implement; and a striker, wherein said control means directssaid motor to store an energy in said energy storage means and saidenergy storage means thereafter releases the energy onto said strikercausing said striker to move from a first position to a second positionsuch that said striker is capable of imparting a force upon saidsurgical implement in at least one direction.
 9. The tool as claimed inclaim 8, wherein the tool further comprises a detent, said detentretaining said striker in said first position until said detent isreleased or overcome thus allowing said energy storage means to releasethe energy onto said striker.
 10. The tool as claimed in claim 9,wherein said detent comprises at least one of a magnet, electromagnet,solenoid, or mechanical interference.
 11. The tool as claimed in claim8, wherein said energy storage means further comprises a valve.
 12. Thetool as claimed in claim 8, wherein the tool further comprises an energycontrol element, said energy control element used to adjust the impactenergy of said striker.
 13. The tool as claimed in claim 8, wherein saidsurgical implement comprises one of a broach, chisel, reamer, and otherend effector.
 14. An orthopedic impacting tool for striking an object,the tool comprising: a motor; a linear motion converter; a piston; anenergy storage means created by a movement of said piston, said energystorage means including a chamber, said chamber operating at less than 9psia for at least a portion of a cycle; a control means; a surgicalimplement; and a striker, wherein said control means directs said motorto store energy in said energy storage means and said energy storagemeans thereafter releases the energy onto said striker causing saidstriker to move from a first position to a second position such thatsaid striker is capable of imparting a force upon said surgicalimplement in at least one direction.
 15. The tool as claimed in claim14, wherein the tool further comprises a detent, said detent retainingsaid striker in said first position until said detent is released orovercome thus allowing said energy storage means to release the energyonto said striker.
 16. The tool as claimed in claim 15, wherein saiddetent comprises at least one of a magnet, electromagnet, solenoid, ormechanical interference.
 17. The tool as claimed in claim 14, whereinsaid energy storage means further comprises a valve.
 18. The tool asclaimed in claim 14, wherein the tool further comprises an energycontrol element, said energy control element used to adjust the impactenergy of said striker.
 19. The tool as claimed in claim 14, whereinsaid surgical implement comprises one of a broach, chisel, reamer, andother end effector.
 20. The tool as claimed in claim 14, wherein saidlinear motion converter comprises one of a slider crank, linkagemechanism, cam, screw, rack and pinion, friction drive, and belt andpulley.